| 1. |
- Ghandi, Reza, et al.
(författare)
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Surface-passivation effects on the performance of 4H-SiC BJTs
- 2011
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Ingår i: IEEE Transactions on Electron Devices. - 0018-9383 .- 1557-9646. ; 58, s. 259-265
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Tidskriftsartikel (refereegranskat)abstract
- In this brief, the electrical performance in terms of maximum current gain and breakdown voltage is compared experimentally and by device simulation for 4H-SiC BJTs passivated with different surface-passivation layers. Variation in bipolar junction transistor (BJT) performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate SiO2 surface passivation on BJT samples from the same wafer. The highest current gain was obtained for plasma-deposited SiO2 which was annealed in N2O ambient at 1100 °C for 3 h. Variations in breakdown voltage for different surface passivations were also found, and this was attributed to differences in fixed oxide charge that can affect the optimum dose of the high-voltage junction-termination extension (JTE). The dependence of breakdown voltage on the dose was also evaluated through nonimplanted BJTs with etched JTE.
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| 2. |
- Nicholls, Jordan R., et al.
(författare)
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A method for characterizing near-interface traps in SiC metal-oxide-semiconductor capacitors from conductance-temperature spectroscopy measurements
- 2021
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 129:5
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Tidskriftsartikel (refereegranskat)abstract
- The state-of-the-art technology for gate oxides on SiC involves the introduction of nitrogen to reduce the density of interface defects. However, SiC metal-oxide-semiconductor (MOS) field-effect transistors still suffer from low channel mobility even after the nitridation treatment. Recent reports have indicated that this is due to near-interface traps (NITs) that communicate with electrons in the SiC conduction band via tunneling. In light of this evidence, it is clear that conventional interface trap analysis is not appropriate for these defects. To address this shortcoming, we introduce a new characterization method based on conductance-temperature spectroscopy. We present simple equations to facilitate the comparison of different fabrication methods based on the density and location of NITs and give some information about their origin. These techniques can also be applied to NITs in other MOS structures.
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| 3. |
- Nicholls, Jordan R., et al.
(författare)
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Near-Interface Trap Model for the Low Temperature Conductance Signal in SiC MOS Capacitors With Nitrided Gate Oxides
- 2020
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646. ; 67:9, s. 3722-3728
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Tidskriftsartikel (refereegranskat)abstract
- The low channel-carrier mobility in commercial SiC MOSFETs has been attributed to fast electron traps labeled "NI." These traps exhibit anomalous behavior compared to other interface trap signals. Furthermore, the electrical parameters extracted from a conventional interface trap analysis of the NI signal are not physically reasonable. To explore the origin of these traps, we fabricated SiC MOS capacitors and measured the conductance across a range of temperatures (between 50 and 300 K). By analyzing the surface electron density at the signal peaks, it is evident that these traps are in fact near-interface traps (NITs)-they are located within the oxide and exchange electrons via a tunneling mechanism. We also developed a model for the conductance generated by NITs and demonstrated a good fit to the experimental data. The knowledge that the NI signal is due to NITs will help in directing future efforts to improve SiC MOSFET performance.
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| 4. |
- Vidarsson, Arnar M., et al.
(författare)
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Detection of near-interface traps in NO annealed 4H-SiC metal oxide semiconductor capacitors combining different electrical characterization methods
- 2022
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 131:21
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Tidskriftsartikel (refereegranskat)abstract
- Fast near-interface (NI) traps have recently been suggested to be the main cause for poor inversion channel mobility in nitrided SiC metal-oxide-semiconductor-field-effect-transistors. Combining capacitance, conductance, and thermal dielectric relaxation current (TDRC) analysis at low temperatures of nitrided SiC MOS capacitors, we observe two categories of fast and slow near-interface traps at the SiO2/4H-SiC interface. TDRC reveals a suppression of slow near-interface traps after nitridation. Capacitance and conductance analysis reveals a high density of fast NI traps close to the SiC conduction band edge that are enhanced by nitridation. The very fast response of NI traps prevents them from detection using TDRC or deep level transient spectroscopy. (C) 2022 Author(s).
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| 5. |
- Vidarsson, Arnar M., et al.
(författare)
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Improvement of channel-carrier mobility in 4H-SiC MOSFETs correlated with passivation of very fast interface traps using sodium enhanced oxidation
- 2023
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Very fast interface traps have recently been suggested to be the main cause behind the rather poor inversion channel mobility in nitrided SiC metal-oxide-semiconductor-field-effect-transistors (MOSFETs). Using capacitance voltage analysis and conductance spectroscopy on metal oxide semiconductor capacitors, at cryogenic temperatures, we find that these fast traps are absent in oxides made by sodium enhanced oxidation, and high inversion channel-carrier mobility in MOSFETs made by sodium enhanced oxidation is observed.
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| 6. |
- Vidarsson, Arnar M., et al.
(författare)
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Observations of very fast electron traps at SiC/high-κ dielectric interfaces
- 2023
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Ingår i: APL Materials. - : AIP Publishing. - 2166-532X. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Very fast interface traps have recently been suggested to be the main cause behind poor channel-carrier mobility in SiC metal-oxide-semiconductor field effect transistors. It has been hypothesized that the NI traps are defects located inside the SiO2 dielectric with energy levels close to the SiC conduction band edge and the observed conductance spectroscopy signal is a result of electron tunneling to and from these defects. Using aluminum nitride and aluminum oxide as gate dielectrics instead of SiO2, we detect NI traps at these SiC/dielectric interfaces as well. A detailed investigation of the NI trap density and behavior as a function of temperature is presented and discussed. Advanced scanning transmission electron microscopy in combination with electron energy loss spectroscopy reveals no SiO2 at the interfaces. This strongly suggests that the NI traps are related to the surface region of the SiC rather than being a property of the gate dielectric.
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